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Version: 23.2.0

HPC compute environments

Tower streamlines the deployment of Nextflow pipelines into both cloud-based and on-prem HPC clusters and supports compute environment creation for the following management and scheduling solutions:


To launch pipelines into an HPC cluster from Tower, the following requirements must be satisfied:

  • The cluster should allow outbound connections to the Tower web service.
  • The cluster queue used to run the Nextflow head job must be able to submit cluster jobs.
  • The Nextflow runtime version 21.02.0-edge (or later) must be installed on the cluster.

Compute environment

To create a new HPC compute environment in Tower:

  1. In a workspace, select Compute environments and then New environment.

  2. Enter a descriptive name for this environment.

  3. Select your HPC environment from the Platform dropdown menu.

  4. Select your credentials, or select + and SSH or Tower Agent to add new credentials.

  5. Enter a name for the credentials.

  6. Enter the absolute path of the Work directory to be used on the cluster.

  7. Enter the absolute path of the Launch directory to be used on the cluster. If omitted, it will be the same as the work directory.

  8. Enter the Login hostname. This is usually the hostname or public IP address of the cluster's login node.

  9. Enter the Head queue name. This is the default cluster queue to which the Nextflow job will be submitted.

  10. Enter the Compute queue name. This is the default cluster queue to which the Nextflow job will submit tasks.

  11. Expand Staging options to include optional pre- or post-run Bash scripts that execute before or after the Nextflow pipeline execution in your environment.

  12. Use the Environment variables option to specify custom environment variables for the Head job and/or Compute jobs.

  13. Configure any advanced options described below, as needed.

  14. Select Create to finalize the creation of the compute environment.

Jump to the documentation for launching pipelines.

Advanced options

  • Use the Nextflow queue size to limit the number of jobs that Nextflow can submit to the scheduler at the same time.

  • Use the Head job submit options to specify platform-specific submit options for the head job. You can optionally apply these options to compute jobs as well:

Once set during compute environment creation, these options cannot be overridden at pipeline launch time.

IBM LSF additional advanced options

  • Use Unit for memory limits, Per job memory limits, and Per task reserve to control how memory is requested for Nextflow jobs.